Blinds having a head rail and a panel of blind fabric suspended from the head rail are well known. Such blinds have a fabric panel which hangs vertically down from a head rail. Mechanism is provided in the head rail for raising and lowering the fabric panel. In many cases the panel is formed into horizontal folds or pleats, although this is not essential. Cords extend down from the head rail at spaced intervals and attach to the lower edge of the panel. Usually the cords run through holes in the fabric, or rings or loops or guides of some kind attached to the rear of the panel, although other arrangements are possible. In many cases the lower edge of the fabric panel contains or supports a rigid rail similar to the bottom rail in conventional venetian blinds. The head rails, and in many cases the bottom rails, are made of metal.
In the past blinds such as this type were usually sold by a salesperson visiting the home. The person would take measurements and write up an order. The blinds were then custom made in a factory, and delivered to the home and installed there.
Currently, in the marketing of such blinds, it is becoming the custom to market these blinds through department stores. Blinds are supplied to the store in standard widths. A customer will measure the actual window or door opening in which he wishes to erect a blind. He will then select a blind of a suitable design, for his taste and his specific window or door. He will then place his order for that blind, in the store. The sales clerk will then locate from amongst the inventory of standard width blinds in the store, a blind of the required design having a width greater than that required by the customer.
The sales clerk will then trim the blind so as to fit the customer's requirement. The cords are located equidistant from each side of the fabric panel. When trimming the width of the blind, each trim cut should be made at an equal spacing from each side edge of the blind. In this way the final trimmed blind has a symmetrical appearance, with the cords being an equal distance from each side edge of the blind, although that distance is less than in the blind before trimming. Trim cutting of the head rail and bottom rail does not require cutting at each end of each rail. This is because the head rail and bottom rail are axially slidable relative to the top and bottom of the fabric panel. Consequently, once the head rail and bottom rail are slid axially relative to the fabric panel, each rail can be cut to length by trimming only one end, of each rail.
Trimming or cutting the metal components, such as the head rail, and the bottom rail if provided, requires a considerable force. However the cutting device, preferably a cutting die, will move only a short distance to make the cut. Usually this distance is no more than the thickness of the metal itself. Various machines are available for trimming blinds. Some use cutting blades. Others use actual profiled cutting dies, especially for cutting metallic head rails.
Examples of such in store point of sale blind trimming machines can be seen in U.S. Pat. Nos. 5,806,394, 6,196,099, 6,178,857, 6,089,134, all of which are owned by Shade-O-Matic Limited, also the owner of the present application.
As explained above, fabric panel blinds are typically formed with pleats or fold lines extending horizontally.
In a preferred form of fabric blind, as explained, the head rail is movable or slidable axially relative to the fabric panel. Similarly the bottom rail will be either movable or slidable relative to the panel, or will be contained within a pocket formed in the lower edge of the panel.
For purposes of trimming, the fabric panel will be folded into pleats in a series of tight folds. Cutting of the panel is achieved by means of a knife blade which slices through the folds of fabric cleanly in a single stroke. These cuts, at each side edge of the panel are made while the head rail and bottom rail are slid axially, to one side. In this way the cutter knife blade can slice through the fabric without also cutting the rails.
The folded fabric is much thicker than the metal forming the head rail and the bottom rail. Consequently the cutting stroke required to cut the folds of the fabric panel is much longer than the cutting stroke required to cut thin metal head rails or bottom rails. However cutting the fabric requires less manual effort than cutting the metal components. Thus either the manual effort required to cut the metal components must increase, as compared with the effort to cut the fabric panel, or the leverage available in the cutting machine, for cutting the metal, must be increased, as compared with the leverage required for cutting the fabric. For this purpose the cutting stroke of the head rail (and bottom rail) cutting die is powered through one transmission system, and the longer cutting stroke for the fabric cutting blade is powered through another transmission system. Both transmissions connect to a single common operating lever, and both are operated by a single manual stroke of the operating lever.